1. Technical Field
The present invention refers to a measuring system for measuring the flow distribution of permeates passing through a filtration membrane and to methods for using such a measuring system.
2. Description of the Related Art
One of the uses of membrane technology lies in the application of membrane bioreactors (MBR) which are used as one component in wastewater treatment plants.
The membrane bioreactor (MBR) as part of a wastewater treatment plant is a compact-built purification system combining the biological degradation step with a membrane separation step. The aqueous part of wastewater fed into an MBR passes through the membrane pores, thus separating the liquid from particulate matters. The liquid that passes through the pores of the membrane is called permeate. This permeate is afterwards discharged (then it is also called “effluent”), subjected to further cleaning treatment or re-used as particle free effluent in wastewater treatment plant.
In membrane-based separation systems, in particular in submerged membrane systems where membranes are subjected to a high biomass concentration of activated sludge, fouling is a major obstacle.
In general, membrane fouling can be defined as the accumulation of particles/substances on the surface of a membrane. Thus, the term membrane fouling comprehensively refers to a series of phenomenon which can comprise of pore adsorption, pore blocking or clogging, gel formation or cake formation.
Fouling can be reversible or irreversible depending on how strong the particles attached to the membrane surface. Reversible fouling can be overcome by periodic backwashing. Irreversible fouling is generally caused by strong particle attachment and this type of fouling requires intense chemical cleaning or membrane replacement.
Since submerged membranes are generally operated under constant flux, a commonly employed measure to indicate membrane fouling under this operating mode is the upsurge of overall transmembrane pressure. However, this parameter has been found to be insensitive for indicating an early state of fouling. Therefore, an early warning of fouling is essential to optimize the system performance. When fouling is insignificant, the permeate distribution is likely to be uniform. As the fouling progresses, a mal-distribution of permeate flow may occur. Thus, it is an object of the present invention to provide techniques which can facilitate the detection of incipient fouling.